Videophone service with which not only voice and sound but also video image can be communicated has started. Patent Document 1 discloses a function to differently sound a ringing tone in a communication terminal, that includes a line control interface interfacing with a network, an information storage in which personal information of a calling party can be registered, a storage in which audio data can be registered, a CPU (Central Processing Unit) detecting whether a calling party places a call from a videophone or a voice telephone based on a call setting information sent to the line control interface, reading first audio data from the storage in accordance with the detection result, detecting a telephone number of the calling party from the call setting information, checking whether the telephone number of the calling party has been registered in the information storage or not, and reading second audio data from the storage in accordance with the result of checking, a ringing controller sounding the audio data read by the CPU, and an audio output portion outputting voice and sound generated by the ringing controller.
According to the invention disclosed in Japanese Patent Laying-Open No. 2003-289345 (Patent Document 1), in order to have information on the calling party easily recognized, the ringing tones are combined in accordance with the information and sounded successively differently, so that the calling party can instantaneously be identified from a remote location.
Separately from the invention according to Patent Document 1, IP (Internet Protocol) telephone utilizing networks has become widely available. Exemplary devices adapted to the IP telephone service include a terminal used alone or a telephone control device for utilizing the IP telephone service. Such a telephone control device includes a router adapted to the IP telephone service or an adapter. These telephone control devices are used by being connected to existing plain old telephone or IP telephone set.    Patent Document 1: Japanese Patent Laying-Open No. 2003-289345